It is important to address gullies in your field to avoid them from growing bigger and bigger. Besides, you are required to repair gullies as part of your conservation plan. The 1985 Food Security Act as amended requires all gullies on Highly Eroded Land (HEL) to be repaired or farmers risk losing government farm payments. After record precipitation events in 2018, so-called ‘ephemeral gullies’ (shallow gullies that can easily be filled in by tillage) have appeared in many farm fields, and reports are coming in that farmers are now working on repairing gullies by filling them in with soil from the bottom of fields. While this may look good for a while, this soil could easily be washed out again when we get another gully washer. These events are expected to be more frequent in the future as our climate is changing, so it becomes the more urgent to fix gullies and then make sure they don’t form again. Unfortunately, we do not have all the answers yet for the best way to address this type of erosion, but here are things that can help:
- Maximize infiltration in the entire field by improving soil health. The more water infiltrates, the less runoff, and the less likely gullies will re-form. To increase infiltration, increase soil organic matter content by growing high-residue crops, sod-crops and tall, vigorous cover crops, leaving residue in the field, spreading packed manure, compost or liquid manure with a lot of coarse material, and using no-tillage practices. Kill cover crops just before planting or after planting the summer crop to maximize biomass. No-tillage is also important because you leave surface residue that protects the soil from the impact of raindrops and this reduces surface sealing due to raindrop impact on the soil surface, and the residue slows runoff, giving water more chance to infiltrate. The organic matter left on top of the soil also stimulates biological activity and this is important to maintain soil structure and macro-porosity. Another important item is to avoid soil compaction that would again reduce infiltration.
- Cover the repaired gully with straw or sawdust to protect it from the elements and to feed soil organisms.
- Plant closely-spaced crops this summer (e.g. drill soybeans instead of planting them) and plant all crops on the contour (across the gully).
- Plan to plant cover crops after summer crop harvest, and plan to use high cover crop seeding rate in the repaired gully area.
- If you expect concentrated flow to happen frequently in the repaired gully area, it may be best to plant a grassed waterway there, or in extreme cases, install permanent structures in the previous channel. If the soil has a seasonally high water table, artificial drainage may help to remove excess water.
Take action now to repair gullies in your field and make sure they don’t re-appear in the future.